1. Field of the Invention
This invention relates to a surge voltage arrester having a gas-tight housing in which electrodes are arranged at a distance opposite one another and, facing one another with their active surfaces, are inserted into the ends of a tubular insulating body which carries at least one coating of electrically conductive material on the inner surface thereof, the coating extending over a part of the tube length of the insulating body.
2. Description of the Prior Art
In order to reduce the ignition voltage in surge voltage arresters, it is a well known practice to provide a coating of electrically conductive material on the tube-shaped insulating body of the surge voltage arrester. For example, reference may be taken to German Pat. No. 1,070,733. These gas-filled surge voltage arresters are basically composed of two electrodes which are fused, in a gas-tight fashion, to an interlying insulating body. The atmosphere in the discharge space is preferably composed of inert gases which do not react with the electrodes participating in the discharge.
The German published application No. 2,032,899 discloses surge voltage arresters in which, in order to reduce the ignition voltage, at least one coating of electrically conductive material is provided on the tube-shaped insulating body of the surge voltage arrester. This coating is in the form of a narrow strip which extends in the direction from one electrode to the other. Narrow strips of this type which facilitate the ignition of the gas discharge path through field distortion on the electrodes are therefore referred to as ignition strips. These ignition strips are arranged on the tube-shaped insulating body such that they are either electrically conductively connected to an electrode, or insulated from the electrodes.
These known surge voltage arresters have the disadvantage that the field electron yield produced by the ignition strips is low because the ignition strips are narrow and only weakly coupled to the electrodes and the asymmetry of the equipotential lines is low.